Ignition contact set



1962 w. o. MANNING, JR 3,048,671

IGNITION CONTACT SET Filed Aug. 31, 1960 2 Sheets-Sheet 1 FIGJ.

INVENTOR. WILLIAM O. ANNING JR.

ATTORNE S 7, 1962 w. o. MANNING, JR 3,048,671

IGNITION CONTACT SET Filed Aug. 51, 1960 2 Sheets-Sheet 2 C 1 B 30 32 ,j A

FIG.3.

60 w (f I 771/ 66 62 \8 M FIG.5.

INVENTOR.

WILLIAM QMANNING JR.

United States Patent 3,048,671 IGNITION CONTACT SET William 0. Manning, Jr., Birmingham, Mich., assignor t0 Holley Carburetor Company, Van Dyke, Mich., a corporation of Michigan Filed Aug. 31, 1960, Ser. No. 53,278 6 Claims. (Cl. 20030) The present invention relates to an ignition contact set. More particularly, this invention relates to an ignition contact set having a pair of movable arms mounted about a common pivot post and means for maintaining the contact points carried by the movable arms at a predetermined setting.

Most of the circuit breaker constructions presently uti lized consist of a stationary contact arm and a spring biased movable arm, each arm provided with a contact point. The arms, in turn, are supported on a breaker plate provided in the distributor housing. This type of construction has certain disadvantages. One of the major disadvantages is that the uncontrolled wear of the rubbing blocks results in an undesirable variation in the relative alignment of the two contact points during operation, thereby preventing the contact points from mating together properly. This affects the performance and lift of the ignition contact set.

The purpose of this invention is to provide means for continually maintaining the contact points of an ignition contact set adjusted to a predetermined setting, and to provide a faster breaking of the contact points. This is accomplished by removing what in most circuit breaker assemblies is the stationary contact arm and replacing it Wih a movable arm which pivots in a manner similar to the conventional movable contact arm.

An object of the present invention is to provide an ignition contact set which includes a pair of movable contact arms movable relative to each other and means for maintaining the contact points carried by the arms at a predetermined setting.

Another object of the present invention is to provide an ignition contact set which is continually adjusted to a predetermined setting.

A further object of the present invention is to provide an ignition contact set which includes a pair of movable arms, means for maintaining the angle between the contact points carried by the arms as originally adjusted, said means including a first spring on the movable arm having the longer lever arm which is heavier than the spring on the other movable arm in order to control the rubbing block wear.

A still further object of the specific invention is to increase the rapidity of the circuit closing operation of the ignition contact set by simultaneously moving two cooperating contact points toward each other from their open position, thereby providing a faster breaking of the contact points.

Still another object of the invention is to provide an ignition contact set which has a pair of movable arms and means for adjusting one of the contact points carried by the movable arms.

A still further object of the present invention is to provide a simplified low cost structure of the aforementioned type having certain advantages contributing to efficiency, reliability and long life, as well as ease of maintenance.

The foregoing, as :well as other objects, will become more apparent as this description proceeds, especially when considered in connection with the accompanying drawings illustrating preferred embodiments of the invention, wherein:

FIGURE 1 is an elevational view, partly in section, of the ignition distributor.

FIGURE 2 is a plan view of the ignition contact set.

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FIGURE 3 is a schematic diagram of the movable contact arms.

FIGURE 4 is a sectional view of the contact point adjustment feature.

FIGURE 5 is a schematic diagram of another embodiment of the movable contact arms.

The present invention mainly consists of an ignition contact set for interrupting an electrical circuit. ,The ignition contact set includes a pair of contacts respectively carried by a pair of movable arms, said arms being mounted for rotation on a common pivot post. A driven cam is provided for pivoting the arms in synchronization to and from a position where the contacts engage each other.

The distributor assembly is represented by the numeral 10 and includes a shaft 12 which is adapted to be geared or otherwise connected to the cam shaft of an internal combustion engine. In FIGURE 1 the shaft 12 is diagrammatically illustrated as connected by gearing 14 to an engine cam shaft 16. The upper end of the shaft 12 is received in the distributor housing 10 and is connected to the usual distributor arm indicated at 18. A cam mechanism, indicated generally by the numeral 20, is carried by the upper end of the shaft 12 for rotation therewith and for small angular adjustment relative thereto and is adapted to operate the ignition contact set indicated generally at 22.

The hollow distributor housing 10 contains a breaker plate 24 which has mounted thereon the circuit breaker assembly 22. An assembly plate 26 is secured to the breaker plate 24 by means of a screw 28. Pivot post 30 is fixed to the assembly plate 26. Mounted for rotation on the pivot post 30 is a pair of movable arms 32 and 34 which carry contact points 31 and 33 respectively. The movable arms 32 and 34 have rubbing blocks 36 and 38 connected thereto respectively. Movable arm 34 has a longer lever arm than arm 32. The lever arm is the distance between the pivot post 30 and one of the rubbing blocks. Movable arm 34 is grounded by contact with the assembly plate 26.

The assembly plate 26 has an upstanding flange, or tab 40 which provides means for anchoring one end of the tension spring 42 which bias the movable arm 32, which has the shortest lever arm, towards the cam 20. A second spring 44 has one end connected to the pivot post 30 and the other end connected to the movable arm 34 so as to bias said arm toward the cam 20. Both arms are biased by the springs in the same direction. Spring 44 is larger than spring 42 in order to result in a controlled wear of the rubbing blocks. This will be described in more detail later on. Tension spring 44 may be mounted in a plurality of different ways so as to permit the arm 34 to move against the tension of spring 44. I It should be understood that the locking screw 28 is provided to secure assembly plate 26 to the breaker plate 24 after the positions of the rubbing blocks 36 and 38 have been set so that one block is on a high portion 46 of the cam 20 and the other block is on a low portion 48. Clearance of the contacts 31 and 33 may be adjusted by having one contact, and in this case contact 33, adjustably movable through locking means 50 as is best illustrated in FIGURE 4. The movable arm 34 carries a threaded bolt 49 avhich has the contact 33 fixed on one end and an adjustable nut 51 on the other end.

Construction of the contact arm 32 is such that the rubbing block '36 carried by movable arm 34 freely extends through arm 32 to engage cam 20. Ignition contact set 22 is properly set when the contacts 31 and 33 are opened and the mating surfaces 52 and 54 are at a predetermined angle to each other. When the contacts are closed, the surfaces 52 and 54 will engage so that both surfaces 52 and 54 are parallel to each other.

One of the movable arms, such as arm 32, may be partially or totally flexible to compensate for any undesirable movement of the arms.

The angle between the contacts 31 and 33, when open, will always remain the same as originally adjusted provided the angular repositioning of the tension arms 32 and 34, due to rubbing block wear, is the same. The rubbing block wear is controlled by providing the tension arm having the longest lever arm with the heaviest spring in order to result in a greater rubbing block wear. In other words, the spring forces on the movable arms are proportional .to the wear of blocks 36 and 38. This proportion is as follows: Where F equals the spring force and W equals the wear:

FIGURE 3 is a schematic view showing the movable arms and the spring means for biasing the arms toward the rotatable cam. For illustration purposes only, as sume that contact A moves .001. The contact B must move the same amount in order to maintain the angle between the arms as originally adjusted. From the construction shown in FIGURE 3, each point on the arms moves in direct proportion to its distance from the pivot post 30.

Since rubbing block A is located at a further distance from the pivot post 30 than rubbing block B, rubbing block A must wear more than rubbing block B in order to maintain the same angle between the two arms. It is therefore necessary to provide the tension arm 34 having the longer lever arm with the heaviest spring in order to result in a greater rubbing block wear of rubbing block A. In order to maintain the same angle between the two arms, it is necessary that the movable contacts, when they deflect due to wear of the rubbing blocks, move a corresponding amount at all times. This is accomplished by providing the tension arm having the longer lever arm with the heaviest spring in order to result in a greater rubbing block wear.

Although this invention has been described as using a pivot post 30 which is common to movable arms 34 and 36, it should be understood that each of the movable arms may be mounted on separate pivot posts as is shown in FIGURE 5. Movable arms 60 and 62 are mounted on pivot posts 64 and 66 respectively and are movable relative to each other. In addition, means previously described are provided for maintaining the contact points A and B on movable arms 60 and 62 respectively at a predetermined setting.

This invention provides desirable faster breaking of the contacts. In present construction, the breaking action is by one movable contact moving away from a stationary contact, whereas the invention provides two movable contacts movable away from each other. The movable arms may be mounted on separate pivot posts or on a common pivot post,

The drawings and the foregoing specification constitute a description of ignition contact set in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. An ignition contact set for use in a distributor having a timing cam comprising a pair of pivotally mounted arms which are movable relative to each other, oppositely facing contact points on said arms, rubbing blocks on said arms which are adapted to engage the timing cam, one of the rubbing blocks having a longer lever arm than the other rubbing block, resilient means for maintaining the contact points continually adjusted to a predetermined setting by controlling the wear of the rubbing blocks due to the timing cam, said means including springs for said arms for biasing said arms in a direction to hold said rubbing blocks in contact with the timing cam, the spring acting on the arm which has the longest lever arm being stronger than the spring acting on the other arm, said arms during the operating cycle of the distributor being responsive solely to the rotation of the timing cam.

2. An ignition contact set defined in claim 1 wherein said arms are mounted on a common pivot post.

3. An ignition contact set defined in claim 1 wherein said arms are mounted on separate pivot posts.

4. An ignition contact set defined in claim 1 wherein one of said rubbing blocks extends through an opening provided in the arm of the other rubbing block so as to engage the timing cam.

5. An ignition contact set defined in claim 1 wherein one of said contacts includes means for adjusting the one contact with respect to the other contact.

6. An ignition contact set for use in a distributor having a timing cam comprising a pair of pivotally mounted arms which are movable relative to each other, oppositely facing contact points on said arms, rubbing blocks on said arms which are adapted to engage the timing cam, one of the rubbing blocks having a longer lever arm than the other rubbing block, means -for maintaining the con tact points continually adjusted to a predetermined setting by controlling the wear of the rubbing blocks due to the timing cam, said means including resilient means for said arms for biasing said arms in a direction to hold said rubbing blocks in contact with the timing cam, the resilient means acting on the arm which has the longest lever arm being stronger than the resilient means acting on the other arm, said arms during the operating cycle of the distributor being responsive solely to the rotation of the timing cam.

References Cited in the file of this patent UNITED STATES PATENTS 1,318,220 Mason Oct. 7, 1919 2,697,762 Buch Dec. 21, 1954 2,711,451 Beaucl-air June 12, 1955 2,854,534 Beauclair Sept. 30, 1958 

